Agricultural machines such as planters, cultivators, fertilizing machines and the like, are used to till fields or to deposit seeds, fertilizer or the like on such fields. To obtain the best result (i.e., even planting, cultivating, or fertilizing), it is preferred that the rows be properly spaced, neither too close nor too far apart.
And it is also preferred that the task be performed as quickly and efficiently as possible without over-cultivating or wasting seed or fertilizer while yet obtaining complete coverage of the field area under cultivation. In other words, efficient machine utilization involves both row spacing and proper manipulation of the operative implement, i.e, the side-by-side seed-planting row units, cultivating discs and harrows or fertilizer hoppers, as examples.
(Machine efficiency is no trivial matter. Modern agricultural machines involve substantial acquisition costs--such machines should be used in a way that maximizes the return on the investment.)
As to row spacing, multi-row machines are configured to perform their tasks in rows which are equally spaced from one another. That is, the operative implements are properly spaced from one another along an axis perpendicular to the direction of travel. Multiple-row agricultural machines are disclosed in U.S. Pat. Nos. 4,582,143 (Pratt), 5,113,956 (Friesen et al.), 5,232,054 (Van Blaricon et al.) and 5,253,717 (Roush et al.).
When using the machine to make multiple passes over a field (as is usually the case), it is also important that an outer row made during a successive pass is properly spaced from the outer row made during the previous pass. That is, the back-and-forth paths of the machine should be properly spaced from one another.
Commonly, this is accomplished by using a marker device which extends laterally from the machine, engages the ground on the "unworked" side of the machine and makes a furrow or other visible "mark" on the ground. This mark establishes a line along which the machine operator steers the machine or the tractor towing the machine.
An agricultural machine having a row marker is disclosed in U.S. Pat. No. 5,484,025 (Landphair et al.). Such patent is assigned to Case Corporation, a leading manufacturer of agricultural machines and the assignee of the invention which is the subject of this specification.
As to the operative implement, the row units, cultivating discs and harrows or fertilizer hoppers must be controlled and manipulated in such a way that the entire area under cultivation is covered with seeds, for example. At the same time, the user wishes to avoid dropping seeds in the non-cultivated ends or side edges of a field since seeds are thereby wasted.
And, often, the operative implement must be raised while preparing to U-turn at the end of a pass. Raising the implement temporarily halts operation of the implement and/or avoids damaging the implement by striking it against the uncultivated area being turned upon.
As an example of the former, the seed-dispensing components of row units are often ground driven by a wheel engaging the ground and mechanically coupled to the components. The only way to temporarily prevent the row units from depositing seed is to stop the tractor (not an acceptable option) or raise the row units.
It will now be appreciated that to raise the implement, make a U-turn at the end of the field and again lower the implement to its operative position takes valuable time. The invention reduces such time in a unique way.
In known agricultural machines, the operator actuates a lever or the like to raise or lower the implement. Once implement movement is initiated, it continues automatically until the implement reaches its maximum height above the ground. This automatic operation is very convenient because when preparing to turn, the operator must also attend to other tasks.
And another convenient feature used on known machines involves marker control. A planter, for example, has a marker switch controlling each of two solenoid valves associated with respective markers. When a marker valve is energized, a hydraulic path is opened from a tractor valve to the marker cylinder. When the tractor valve is moved to the "raise" position (to raise the implement), that marker, the solenoid of which is then energized through the marker switch, is also raised. That is, its hydraulic cylinder in then in parallel with the hydraulic cylinder raising the implement.
To put it in different words, operation of the marker switch causes the appropriate marker to be extended and the other marker to retract. The height of the switch above ground is adjustable over a range of several inches. However, marker switch position only affects that implement height at which such implement operates the switch and has no bearing upon the height to which the implement itself is ultimately raised.
With machines such as describes above, the resulting maximum implement height above the ground is often well in excess of that needed to achieve the above-described result of avoiding striking uncultivated dirt or temporarily halting implement operation. And, clearly, the time required to bring the implement to maximum height affects the overall "cycle time" and, consequently, the productivity of the machine.
A new circuit and method which improve machine efficiency and reduce overall cycle time would be an important advance in the art.